style: 添加 ServiceImpl 注释。

mybatis-flex-solon-plugin/src/main/java/com/mybatisflex/solon/service/impl/ServiceImpl.java

@@ -1,4 +1,4 @@
-/**
+/*
  *  Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
  *  <p>
  *  Licensed under the Apache License, Version 2.0 (the "License");
@@ -19,6 +19,12 @@ import com.mybatisflex.core.BaseMapper;
 import com.mybatisflex.core.service.IService;
 import org.noear.solon.annotation.Inject;
 
+/**
+ * 默认 {@link IService} 实现类。
+ *
+ * @param <M> Mapper 类型
+ * @param <T> Entity 类型
+ */
 public class ServiceImpl<M extends BaseMapper<T>, T> implements IService<T> {
 
     @Inject